GoDaddy has an interesting article that will give you a general overview:
Google also has posted their Webmaster Guidelines that will help Google find, index, and rank your site.
Both are good starting points!
SEO or Search Engine Optimisation is basically gearing your site so that it's easier to find it in a goggle search for example.
I have purposely given you an unbiased Wikipedia link for one simple reason, there are unfortunately lots of scamming sites who will take your money if you don't do your homework! That's because they will promise you 1st Page on Google search, for $$$$$, take your money and run.
You must educate yourself about how to manage SEO yourself, to save money.
Wordpress has YOAST and Godaddy also have applications, but with some knowledge you can do it all yourself freely.
A lot of things play into SEO, but the one thing the 'snake oil' doctors won't tell you when offering their magic bullets (there aren't any) is that of good content. It's all well and good getting seen, but if your site hurts the eyes or takes forever to load...................
Anyhow, the link there will put you on the right track....... good luck!
edit... Hi @Muse, I didn't see you until I posted my reply
Yes @Muse has given you some good pointers too